Electrophotographic copying machines and the like usually include a corona discharge device for transferring toner images formed on a photosensitive member onto paper. The use of a corona discharge device nevertheless involves a problem in that ozone produced by the discharge exerts an adverse influence on the photosensitive member.
FIG. 1 shows a corona discharge device 1a already proposed to overcome this problem. This known corona discharge device 1a is disposed under a photosensitive drum 2a and has a discharge wire 11a extending axially of the drum 2a and a stabilizer plate 12a surrounding the discharge wire 11a on opposite lateral side and on a lower side. The stabilizer plate 12a is formed at its bottom with an ozone discharge opening 13a for drawing air therethrough to discharge ozone from the device.
With the device 1a, however, paper P close an hopening 14a in the upper side of the device 1a when passing over the opening 14a, consequently impeding the flow of air therethrough to produce a negative pressure within the device 1a. Accordingly, the device has the drawback that the rear end of the paper P, when passing between the device 1a and the drum 2a, is separated from the drum 2a, making it impossible for the device to transfer the toner image properly.